Per Valentin Aass, pioneer in freshwater fish research, dies at 99

Norway has lost a leading figure in freshwater fish research with the passing of Per Valentin Aass, who died on May 17, 2026, at the age of 99. Aass was a pioneer and a cornerstone in his field, leaving behind a legacy of significant scientific contributions.

Born on September 2, 1926, Aass completed his master's degree in 1953 with research on char in Pålsbufjorden. He furthered his academic achievements by earning a doctorate from Uppsala University in 1973. His seminal works on trout and char, particularly concerning their relationship with watercourse regulations, are now considered classics in the field.

Aass's expertise made him a sought-after expert witness in watercourse disputes during the 1960s and 1970s. His solid research and professional insight were invaluable in these proceedings. Over a career spanning nearly 75 years, Aass made substantial societal contributions, a dedication recognized in 2012 when he was awarded the King's Medal of Merit.

Beyond his academic pursuits, Aass was also an active athlete, competing in various running events for Ready during his student years. His passing marks the end of an era for Norwegian ichthyology.